CA1101272A - Ballistic projectile - Google Patents

Abstract

913,223 ABSTRACT

Ballistic projectiles for subsonic propulsion having a helically twisted body portion and a tapered nose portion and having an apparent density of up to 5 g/cm3.
The projectiles can be propelled through barrels having a complementary barrel without objectionable fouling.

Description

913,223 BALLISTIC PROJECTILE

The present inventlon relates to sub~sonlc ballistic projectlles having a unique comb~nation of body shape and apparent density The projectiles can be propelled ~rom a smooth bore barrel wlth spin about the 'longitudinal axis ~mparted thereto, Due to their physlcal and ball~stic characteristics the proJectiles are part~
cularly suited for the ballist~c impact on and/or implantation in living animal bodies.
Balllstically implantable projectlles containing biologically act~ve materlals ~or implantatlon into living animal bo~es have been dlsclosed in U.SO ~ ~
Patent 3,948,263 ~ssued"April 6, 1976, and U.S. Patent ~ ';
3,982,536 lssued September 28, 1~76 These proJectlles inherently have a low apparent density and provide the ~ ' capability of obtainlng precisely controlled ballist~c implantation within a tar~get, such as an animal body.
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However, the low density materials used ;n these ballis- -h ' tlc projectiles cause ~ouling problems when shot through conventional land and g~oove barrels whlch provld'e spin ' `~
stabilization o~ the pro~ectiles~
The present lnvention overcomes the foul~
ing problem associated with the known ballistically implantable proJectiles by providing a proJectile havlng a unique combination of hellcal body shape and apparent density. These pro~ectiles can be proJected from a barrel havlng a smooth, helical bore ~n a spinning mode, preferably with sufficient spin about the longitudinal axis to stabillze the ~lfght of the proJectile, by a mechanical or expanding gas propulsion means without objectionable fouling of the barrel.

Prior to the present invention, lead pro~ectiles hav~ng helically shaped polygonal bodies were used to achieve extreme accuracy in target r~fles ~;
and other ~irearms. Brit~sh Patent No, 2410 issued in 1855 and Patent No~ 1645 issued in 1857 show the use of lead bullets having a helical polygonal body and a complementary hel~cally bored barrel, Articles treatlng the history of guns and bullets dlscuss these flrearm systems. Of interest is the book "Guns through the ~-Ages" by Geo~frey Boothroyd, Crown Publishers, Inc., tl968), (Lib. Congress, Cat. Card. No. 62~15152), at pages 80~85, which describes the lJhltworth hexagonal twisted bore and the Lancaster tw~sted oval bore.
The Wh~tworth rl~les, wh~le belng extremely accurate~ were not favored s~nce the r~le "~ouled very badly after about 20 shots!' ("Guns~', supra, 84) and required a special scraper to clean the bore after each shot, Accordingly, it is qu~te surprising that the i-projectiles of th~s invent~on do not cause obJectlonable fouling when propelled through a complementary barrel~
The ballistic pro~ectlles o~ this inven~
tion comprlse an elongated body portion and a tapered nose portion. The pro~ectile body has a conflguration which can be geometrically inscrlbed longitudinally within the volume enclosed by an lmag;nary sol;d helix generated by revolving a non~circular plane figure at a ~`
constant rate around an axis contained within and perpend~
cular to the plane of the ~lgure whlle s1multaneously moving the plane figure along the perpendicular ax1s at a constant rate. The imaglnary helical volume thus has '7Z

a constant p~tch~ The ax~s ls preferably at the geo-metrlc center o~ the plane figure.
The plane flgure used to generate the helical volume must have a non~circular perimeter wherein all extended, lmaginary, straight lines circumscribing, i.e., tangent to, the perlmeter o~ the plane flgure intersect at a po~nt on or outslde of the perimeter.
At least the bearing surface portions o~ the Inscrlbed proJectile, i.e,, those surfaces which adJoint the surface of the hellcal volume~ have the contour of the helical ; volumeO Preferably, the body o~ the pro~ectlle is -~
constructed so that no open path exlsts, wlth~n the heltcal volume, which extends along the complete length of the projectile body. That ls, the pro~ectile body plugs or seals the hel~cal volume so as to prevent the passage of another body or material therethrough. This is necessary when the pro~ect~le ls to be propelled by an expand~ng gas propuls1On means so that the proJec~
tlle body can "seal" the complementary barrel to preven~
gas leakage therethrough~ Wlth mechanlcal propulsion means the sealIng feature Is not a necess~ty.
~ Further, the pro~ect~le must have a relat~vely low apparent density~ The apparent denslty should be about 5 grams/cm3 or less~ Preferably the apparent density w~ll range-from about 1 to about 3 grams/cm3 and most preferably from about 2 to about 3 g/cm3~ The apparent denslty is obtained by divldlng the total mass of the proJect11e, in grams, by the apparent volume, 1n cubic centimeters. The apparent volume ls the volume contained wlthin the exterior surface of the pro~ectile, including the volume of cavities and voids formed withln the proJect~le, even though such cavlties may commun~cate w~th the exterior of the pro~ectile. Thus, the apparent volume of a projectile having a cav1ty opening to the rear of the projectile is the same as the volume occupied by a completely solid pro~ectile having the same exterior conflguration and d~mensions, Merely adding a cavity to, or creating voids in, the projectile does not change the apparent volume as de~ined herein.
Advantageous results are obta;ned when the projectiles of this lnvention are propelled, at subsonic muzzle velocities, through a complementary barrel, that is, a barrel having a helically twisted bore of the same configuration and dimension as the imaginary helical volume circumscribing the projectile to be propelled through the barrel, the bore of the barrel being free of the internal projections con~ained in conventional land and groove barrels.
In one embodiment of the projectile, the helical volume ;n which the pro~ectile is inscribed is formed by the rotation of a polygon, preferably a regular polygon, figure around and along the axis as describedO
The proJectiles according to this embodiment would have a body surface comprising a plurality of planar sides twisted around the longitudinal axis of the body to form a helical polyplanar body surface.
In an alternative embodiment of the inventlon the helical volume 1n which the proJectlle ls inscribed ~s formed by rotatlon of a curved, non;circular flgure, such as an elllpse~ around the axis as descr~bed hereinabove. Th~s provldes a proJect11e havlng a hel~cally curved body surface analogous to a threaded bolt, screw'i twïst drill or s1mi1ar helically shaped article ~
In yet another embodiment, the helical ~ ;
volume in whlch the projectlle is lnscrlbed ~s ~ormed by the rotatlon o~ a plane flgure having both curved and stralght perimetrlc port~ons. Such an embodlment provides a projectlle havlng at least one "~lat" or planar portion hel~cally tw~sted around and along the proJectlle~
As used herein the term non-c~rcular -means that the perlmeter is not a complete, perfect circle. It ls contemplated, however, that portlons of the perlmeter may comprlse arcs havlng a constant radlus - lnclud~ng embodlments where1n the plane generat~ng f~gure descr~bed here7nabove has one or more stralght sides but ls otherwlse clrcularO Thus~ the term non~ -c~rcular lncludes a varlety of curved perlmeters, ~; polygonal, trlangular and rectangular per~meters, as ~;
well as perlmeters hav~ng comb~nat~ons of curved and straight portlons~ `~

- . . : : -The projectiles can be constructed to carry a -variety of payloads if desired. The~ are particularly useful for treating and/or labeling animals by ballistic contact with or implantation in the animal. When used for the treatment of ani-mals, the projectiles may be made to carry one or more of a variety of biologically active materials such as vitamins, ~
minerals, tranquilizers, antigens and the like. The projectile ~-and/or its contents may be formulated or structured to provide either or both of delayed or sustained release of the biologi-cally active contents. The projectile may also contain an identification or labeling element such as a dye or other coloring means or electronic detectlon elements.
Accordingly, the invention is broadly claimed herein as a ballistic projectile comprising an elongated body portion and a tapered nose portion characterized in that said projectile can be subsonically propelled from a smooth bore barrel with spin about the longitudinal axis imparted thereto, said pro-jectile body having a configuration which is inscribed longitudi-~ nally within the volume enclosed by an imaginary solid helix 20 generated by revolving a non-circular plane figure at a constant rate around an axis contained within and perpendicular to the plane of said figure while simultaneously moving said plane figure along said perpendicular axis at a constant rate, said plane figure having a perimeter wherein all imaginary, extended, straight lines circumscribing the perimeter of said plane figure intersect at a point on or outside of said perimeter, at least the surface portions of said inscribed projectile body adjoining the surface of said helical volume having the contour of said helical volume, said projectile having an apparent density up to about 5 grams/cm3~

Figure 1 is a side view of a projectile of the present invention showing optional cavities and ballast or labelling 7;~

means in phantom.
Figuxe 2 is a rear view of the projectile shown in Figure 1~ .~
Figure 3 is a top sectional view of a mounted barrel having a smooth helical polygonal bore complementary to the body of the projectile of Figure 1.
Figure 4 is a cross-section view along line 4-4 of the barrel of Figuxe 3.
. Figure 5 is a perspective view of an alternative 10 embodiment of a projectile showing optional cavities and ballast :
or labeling means partially in phantom.
Figure 6 is a xear view of the projectile shown in ~.
Figure 5.

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FIGURE 7 is a cross~sectlon at a po~nt along a barrel s~milar to that shown ln Flgure 3 but having a smooth helicall~ twlsted bore complementary to the body of the pro~ectile o~ Figure S, Referring now to F~gure 1, there is shown a pro~ectlle 10 comprising elongated body 12 and tapered nose 14. Body 12 has a sur~ace defined by ten ~nter~
secting planes to form s~des 16 helically disposed about : the axis "a" of pro~ect~le ;10.
As described herelnbe~ore, the body of the :
projectfle is of a shape which can be inscribed withln the hellcal volume ~ormed by the constant movement of a regular decagonal plane f~gure around and along axis "a" and wherein at least portions of the surface of the projectile body have the contour of the helical volume so formed. The projectile thus has an exterior surface having bearing portions whlch wlll bear upon the lnterlor surfaces of the bore of a complementary barrel and wlll fol1Ow the helical path of the bore along the barrel.
This allows the projectile to rotate about the longi-tudinal axis as it progresses along the barrel and will exit the barrel ln a sp~nning modeO Preferably, the projectile w~ll exit the barrel with su~lcient rotation-al veloc~ty to stabilize the proJectile durlng ~llght.
- 25 The rate o~ rotation can be controlled by the pitch of the hel~cal surface of the proJectlle body and comple-mentary bore as descrlbed here~na~terO
While projectlle 10 is shown as hav~ng 10 sldes which provlde a body cross sectlon havlng a regular decagonal perimeter, the body surface may `7~

comprlse any number of sldes from 3 up to about 20 or more. As a pract~cal limlt the max~mum number of s~des for a proJectile having a diameter of about 0.6 cm should ~ -not be in excess of about 20 since beyond this po~nt the perimeter of the cross section of the body approaches a circle and the pro~ectlle may have a tendency to ride over the s~des of the bore o~ the barrel wlthout achieving the deslred rotational pattern for spin stab zation. The minimum number of s~des on the proJectlle is dictated by stability consideratlons~ A proJectile hav~ng large sides tends to be more read~ly a~fected by air currents durlng flight. It ~s pre~erred to maintaln the wldth of the sldes w~thln the range of about 0.1 cm.
to about 0.4 cm. and that the s~des be of equal width.
lS Thls corresponds to a range o~ about 5 to about 20 sides for a pro~ectile having a nomlnal maximum d~ameter of about 0.6 cm~ For a body havlng s~des of equal width the relat~onsh~p ~s conven~ently g~ven by Standard mensuration formulae, When the body has s~des of unequal wldth, it ~s pre~erred that the wldth o~ all of the sides fall wlthin the range spec~fied above, lOe , a width of between 0.1 cm. and 0 4 cm.
As can be appreciated, the body surface of a larger dlameter pro~ectlle can accommodate a greater number of sldes, wh~le a smal7er d~ameter proJec-t11e must have fewer s~des to maintain the preferred 0.1 cm. min~mum slde w~dth.
The p1tch of the hellcally dlsposed sldes of the proJectile can be se7ected over a wide fange, bu~
the pitch should be selected to ~mpart adequate fllgh~ ;~

V _, r stabilizing spin to the projecti'le. The pitch must be constant for each projectile. The pitch of the helix is the dfstance between two coils of the hel1x measured along the longitudinal axis of the body, In other words, the pitch is the distance in whfch one of the helically dlsposed s~des o~ the body completes or would complete one full revolution around the body. Preferably the pitch is between l8 and 40 cm. and is most preferably ' about 20-25 cm. to provide aprojectile having a "1 in 20"
to "1 in 25" twist.
If the helical pitch of the projectile is greatly lengthened, the projectile will not achieve sufficient spin to be properly stabilized during flight. If the pitch is excessively short, the projec-tile will offer greater resfstance to movement along a complementary bored barrel. Greater propulsfon forces w~ll be needed to achleve the des;red muzzle veloci'ty.
This condition may in turn produce increased friction forces in the barrel, resulting in objectionable wear-fng and fouling.
Projectile 10 is shown fn Figure 1 as includ;ng a cavity defined by annular wal'l 18 opening to the rear of the projectile The cavity is optional and can be used to carry a variety of beneficial pay7Oads as will be described in greater detai'l herei'nafter.
Mass 20 is also shown embedded within proJecti'le 10.
'The mass may be a ballast means, to stabilize the proJec-tile during flight, or may be an active or passai~e ident;fying or labeling element such as the passlve transponders, i'Oe., tuned, resonant cfrcufts, desc~ibed in u.S~ patent 4,065,753 granted on December 27, 1977 ~ 9 ~' 1 r.- ~ 5'`~

and UOS. patent 4,087,791, granted on M~y 2, 1978.
Nose portion 14 is tapered to provide the deslred fl~ght and penetratlng characterlstics, depending on the preferred target. Various ogival desfgns, '~-such as rounded and sharp pointed designs, are known in the conventional ballist;cs art and can be found in a variety of ballistic texts. These designs can be adapted ; for use with the projectiles of the present inventiondepending on the spec~fic term1nal ballistics charac~ ;
teristics desired~
Figure 2 ~s a rear view of the pro jectile lO shown in Flgure l, show~ng the cavlty defined by annular wall l~ within body 12. Ten hellcally dis-posed planes 15 form the s~des o~ the sur~ace o~ body 12.
Figure 3 ls a cross section view along ' the length of barrel 30 which is ~hown retalned ln mounting block 32~ Barrel 30 comprises breech 34 and bore 36. The bore 36 is smo~th, that ;s, the bore has 20- no internal project~ons such as are characteristic of conventlonal land and groove barrels~ Rather, bore 36 comprises ten sides 38 helically disposed about the - longitudinal axls "b" of bore 36~ The diameter and pitch of he'lical bore 36 are complementary to the body surface of projectile 20 shown in Figure l~ That is, the bore has a contour and d~mensions identical to the imaglnary helical volume circumscriblng the pro~iectgles which are ,~
to be propel'led through the barrel. ~hus, the bore 36 coincides with the volume ~ormed by the rotation of -the regular decagonal plane flgure, as descri'bed wfth respect to projectile lO hereinabove, around and a'iong axis ~b~o , ~ . ,~
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ProJectile 10 can be propellPd through barrel 30 whereby sides 16 of projectile 10 will contact and follow the complementary sides 38 of bore 36 so that as proJectile 10 moves through barrel 30, the projectile is forced to rotate about longitudlnal axis "a" and exits the muz21e of the barrel in a spinning mode.
Figure 4 is a cross sectlon taken along line 4-4 of barrel 30. Bore 36 is shown having a deca-gonal perimeter formed by sides 38.
As noted hereinabove, the decagonal per~-meter can be circumscribed by ~maginary, extended, stralght lines which coincide with the straight sides of the per~meter. All such extended llnes wlll inter~
sect at a polnt either on or outside of the perlmeter.
It is critlcal that the project~le bodies of this invention have helical sur~aces which meet this require-ment. Bodles having cross sectic)n perimeters whereln such lines intersect within the perimeter would have indentations thereinO The complementary barrels would thus be requlred to have projections in the bore to mate with the projectile properly and would not be smooth bored as defined herein, This combination would produce objectionable fouling.
Figure 5 ~s a perspectlve view showlng an alternate embodiment of the invention where1n projec-tile 40 comprises a body port1on 42 and a tapered nose portion 44. The cross section of body 42 is elliptical as shown by the rear view of proJectile 40 ~Figure 6~o The body 42 has a curved surface which is helical`ly twisted about longitudinal axis "c". An optional 3Ll~lZ7Z
, cavlty def~ned` by annular wall 46 is shown opening to the rear of the proJect~le 40. This cavity may be used to carry and release, if desired, a var1ety of payloads.
In addition, other mass represented by cube 48, shown in phantom, can be ~ncorporated in the pro~ectile 40 to advantage as discussed wlth respect to the projectile shown ln Figure 1.
As described here~nbefore, the body of this projectile can be inscribed wlthln the helical volume formed by the constant movement of an elliptlcal plane f~gure around and along axis l'c" and wherein the surface of the pro~ect~le body has the contour of the helical volume so formed. The ell~pt~cal plane figure should have significantly d~fferent major and m~nor d~ameters so as to be non~c~rcular and so that a spin about longi~
tudinal axis '`c" can be imparted when the project~le is propelled through a complementary barrel. The d~fference between the major and minor diametershould not be so `~
great as to prov~de a projectile which will be excessively af~ected by alr currents during ~llght. It is preferred that the length of the minor diameter be about 50 to 90% of the length of the major diameter. The requirements for the proiectlles hav~ng curved surfaces are analogous to those for the projectiles having cross sections with ,~
polygonal perimeters as d~scussed wlth reference to Flgure 1 hereinabove, Figure 7 shows a cross sect1On of a barrel similar to barrel 30 shown in Figure 3, but ^navlng a smooth helical bore with curved walls 52 forming an elliptlcal perimeterO Barrel 50 ls complementary ~ 12 ~

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in contour to the body o~ projectlle 40 shown in Figure 5 so that as proJectile 40 ls propelled through barrel 50, the projectile is caused to rotate about axis "c"
and exit the muzzle of the barrel ln a splnn~ng modeO
As with the polygonal cross section per~meter shown In Figure 1~4, the ell~ptical per~meter of the pro~ectile and bore in Flgure 5~7 can be c~rcum~ ~`
scribed by a serles of Imag~nary extended straight lines tangent to the perimeterO For the reasons set forth with respect to the polygonal structures described ~ ~
herein, these llnes must not lntersect within the ~ -perimeter in order to be ~ncluded within the structures contemplated by thls invention.
Projectiles accordlng to the present lS invention can be prepared ~rom any material which has sufficient integrity to be ~ormed lnto a pro~ectile and propelled from a gun barrel at subsonic muzzle velocities without fracture. Further, the material must provide a finished proJectile, including payload if any, which provides the necessary apparent density.
A variety of materials can be used to form the pro~ect;lesO Materials having a density below that of the heavy metals, such as lead, are preferred in order to provide the required mass characteristlcs~
Generally organic materials are preferred, although certain lightweight metals~ such as magnesium, can be used with advantage, The preferred organic materials are polymeric materials such as the various thermo-plastic and thermosetting polymers~

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When the projectiles of th~s inventi'on are used to be ~mpacted on, or lmplanted in~ anima'ls, it is preferred that a biomed~cally acceptable organic material is used.' These materials can also be selected so as to be soluble or ~nsoluble in the target animal body after ballistic ~mplanatation of the projectile.
Exemplary of relatively insoluble materials are the synthetic organic polymers such as the polyolefins, e.g., polyethylene and polypropylene, polysiloxanes;
polyamides, such as nylon, ~luorinated hydrocarbon resins;
ABS polymers and the like. Exemplary of polymers whlch are soluble in animal bodies, e.g. c`attle, are the cellulose derivatives, such as hydroxy propyl cellulose.

Metallic projectiles can be usèd for ~ ' certaln appl;cations. Magnesium is 'light in weight and can be dissolved by body fluids and thus projectiles of magnesium or combinations o~ magnesium and organic polymer, e.'g. either the exterior or interior comprislng mag-nesium, can be used. While lead is not a preferred material, lead may be incorporated into the proJectlle as a weight or ballast means or as a coating on the projectile. However, because o~ possible toxicity, lead is not generally desirable for implantatlon into an animal body where it can be exposed to the body, e,g., as a surface coatlng or in an otherwise soluble proJectile. Moreover, pro~ectlles having a surface coating of metallic lead have a greater tendency to smear and foul the barrel from wh~ch they are propel'led ~` 1 '1 - ' .,~,. .

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due to the peculiar physical nature of lead. Accordingly, project~les whtch have a surface substantially ~ree of metall~c lead are pre~erred ~or use ln this Invention.
A var~ety of inoryanic f~llers such as calcium carbonate, magneslum carbonate, ferric o~des, iron powder and the 11ke can be used to alter the solubility propert~es and/or the dens~ty and other phys~cal propert~es of the proJectiles.
For certaln appllcations ~t may be desired that the pro~ecttle rupture on impact with or w~thout significant penetration, ~or example, to release a dye or a med1cament, such as an antisept~c material or a tranqu~llzer. Certain waxes or ~rag~le polymeric mater~als can be used to achieve these results w~th the whole pro~ect~le or only a portlon thereof, such as the nose port~on, made from t~e rupturable materlal~
Lubrlcants which may a~d in the molding and shooting of the pro~ectiles can be ~ncorporated into the project~7es, Calcium stearate, glycerol monostearate, powdered te~lon and the llke can be used with advantage.
The projectiles of the present invention can be formed with internal cavities in which various types of beneficial payloads can be incorporated. The - cavity may be left open or sealed with a removable, soluble or porous plug so that the payload can be dissem1nated ~ollowing implantation into the animal.
Various types o~ bene~cial payloads and various means of provid~ng sustained release of the payload can be employed such as are descr1bed ln U.S~ Patent 3,948,263, issued Apr~l 6, 1976 and U.S. Patent 3,982~536, lssued ~ 15 ~

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September 28, 1976.

OF partlcular interest ~s the fabricatlon of completely soluble projectiles made from hydroxypropyl cellulose or other body-soluble polymer. The payload can be carried in a cavity in the body of the projectile or admixed and dispersed throughout the solid body of the projectile.~ After implantation, the projectlle completely dissolves ln the body, releasing lts contents in the animal. Also of interest are the `'solid dose" projec~ -tlles where the projectile comprises up to about 95%
by weight active ingredlent with the remainder belng a blologically acceptable binder. Thus~ proJectiles comprising 90-95~ penicillin and 5~10% hydroxypropyl cellulose binder can be molded irlto the shape o~ a projectlle and used ln accordance with thls lnvention. ; ' As noted prevlously herein, the projec-tlles of this inventlon can be propelled from comple-mentary barrels without ob~ectionable fouling even after ,~
extended use, e.g~ several hundred shots. In contrast, pro~ectiles prepared from similar materials whlch have round bodies, and which are propelled through conventlonal land and groove barrels to provide sp~n stabillzation, show evidence o~ fouling after one hundred shots or less and must be periodlcally cleaned to provide maximum ~ performance over an extended period of use. The proJec-'~ tiles of the present invention thus provide a distinct advantage over the known low density projectiles parti-cularly underfleld conditlons where periodic cleani'ng is not practical.
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The lnventlon can be further illustrated by reference to the ~ollowing examples.

Project71es similar to that shown gn Figure 1 were prepared by ln~lection molding technique.
An ~ntimate mixture of 50 parts hydroxypropylcellulose and 50 parts calc~um carbonate was formed by dissolving the hydroxypropylcellulose In 250 parts methanol and ;
stirrgng in the calcium carbonate to ~orm a thgck slurry.
The solvent was removed by alr drygng and the resulting cake was crushed and used to injection mold projectiles using a decagon mold having a 25 cm, hellcal pitch. The projectiles had an apparent density of ~bout 2 g/cm3.
These projectiles were propelled through a complementary barrel at subsonic muzzle velocities.
After several hundred shot no ob~ectgonal barrel foul-ing in the form of deposits in the barrel or signiflcant loss of velocity occurred. When conventional round bodied projectlles were prepared from the same matergals - 20 and propelled through a conventional, round land and groove barrel, the barrel showed evgdence of fouling and required cleaning for extended use.

A .25 caliber (6.35 mm) proJectgle sultable for long term implantation ln cattle and havgng a helical decagon body configuratlon slm1lar to that shown gn Figure 1 was prepared from polyethylene by inJection molding. A small passgve transponder was nserted gnto the center cavity of the proJectileO The remainder of the cav~ty was ~llled wgth epoxy resin which L2~2 was cured ~n place and the proJectlle was then ster11ized by exposure to ethylene oxide. The project~le had an apparent dens~ty of about 2~5 g/cm3.
These projectiles could be propelled through a complementary decagon barrel wlthout obJectlon-able fouling. When Implanted into cattle, the implant sites showed no adverse tlssue reaction to the ~mplantO
The implanted transponder could be detected by remote electronlc detectlon devices A project~le which can be d~ssolved or ;
degraded ln the tissue of an~mals was prepared by in~ectlon mold~ng a pro~ectlle slmilar to that shown 1n Figure l, and having a cavity there~n, from hydroxy-propylcellulose, The decagon project~le was then sterllized w~th ethylene oxide. A pellet of dry vaccine (Clostridium haemolyticum bacter~in) was pressed lnto the cavity. The loaded pro~ect~le had an apparent dens1ty of about 2 g/cm3.
These projectiles could be propelled ; from a complementary decagon barrel without objectlonable fouling of the barrel after hundreds of shots. When balllstlcally Implanted into cattle, the projectile was found to have d~ssolved ~n the body ln about 24 hours.

A project~le s1milar to that shown ln Figure 1 was prepared from a composltlon conta7nlng a hlgh loading o~ peniclllln, Ten parts of hydroxypropyl-cellulose was d~ssolved ln 500 parts of methanol. 90 parts of potass~um penlc~ n G was stlrred lnto the ~ 18 , ,. , : - . ~

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liquid to form a homogeneous slurry~ After alr drying the slurry to remove the solvent~ the caked mixture was ~inely ground. The resulting powders were then compacted lnto a hellcal decagon mold havlng a 25 cm pitch to provlde proJectlles w~th an apparent density o~
about 2 g/cm3.
These pro~ectlles could be propelled through a complementary decagon barrel without objection~
able fouling, When ~mplanted`into cattle the projectile dissolved in the animal body within about 24 hours.

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Claims (18)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A ballistic projectile comprising an elongated body portion and a tapered nose portion characterized in that said projectile can be subsonically propelled from a smooth bore barrel with spin about the longitudinal axis imparted thereto, said projectile body having a configuration which is inscribed longitudinally within the volume enclosed by an imaginary solid helix generated by revolving a non-circular plane figure at a constant rate around an axis contained within and perpendicular to the plane of said figure while simultaneously moving said plane figure along said perpendicular axis at a constant rate, said plane figure having a perimeter wherein all imaginary, extended, straight lines circumscribing the perimeter of said plane figure intersect at a point on or outside of said perimeter, at least the surface portions of said inscribed projectile body adjoining the surface of said helical volume having the contour of said helical volume, said projectile having an apparent density up to about 5 grams/cm3.

2. A ballistic projectile according to claim 1 wherein said projectile body is constructed so that within said helical volume no open path exists which extends along the complete length of the projectile body.

3. A projectile according to claim 1 wherein said plane figure has a polygonal perimeter.

4. A projectile according to claim 3 wherein said polygonal perimeter is decagonal.

5. A projectile according to claim 1 wherein said plane figure has a substantially elliptical perimeter.

6. A projectile according to claim 1 wherein said body has a surface substantially free of metallic lead.

7. A projectile according to claim 1 wherein said body comprises a biomedically acceptable organic polymer.

8. A projectile according to claim 6 wherein said projectile contains a biologically active material.

9. A projectile according to claim 8 wherein said biologically active material is an antigen.

10. A projectile according to claim 8 including means for providing sustained release of said biologically active material.

11. A projectile according to claim 8 wherein said biologically active material is carried in a cavity in the body of said projectile.

12. A projectile according to claim 1 wherein said projectile is soluble in the fluids and cells of a living animal body.

13. A projectile according to claim 12 wherein a biologically active material is dispersed throughout said soluble projectile.

14. A projectile according to claim 13 wherein said biologically active material comprises up to 95% by weight, based on the total weight of the projectile, of biologically active material.

15. A projectile according to claim 1 containing a remotely detectable labeling means.

16. A projectile according to claim 15 wherein said labeling means comprises a transponder.

17. A ballistic system for propelling a projectile in a longitudinally oriented spinning mode comprising a projectile according to claim 1 contained within a barrel having a complementary, smooth, helical bore and means for propelling said projectile from said barrel.

18. A ballistic system according to claim 17 wherein said propulsion means is an expanding gas means.